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Particle detection methodParticle detection method description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20060203234, Particle detection method. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS REFERENCE TO RELATED APPLICATION [0001] This application is a divisional of U.S. Application Ser. No. 10/666,586, filed Sep. 18, 2003. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present disclosure relates generally to the fabrication of integrated devices, and more particularly, to the detection of particles on substrates used in the fabrication of integrated devices. [0004] 2. Description of the Related Art [0005] Particulate contaminants are undesirable in the fabrication of integrated devices. As feature sizes continue to shrink, particulate contamination becomes increasingly troublesome. A single particulate contaminant in the wrong place can create a "killing defect," rendering an entire integrated device non-functional. In addition to the location of the particle, its composition can make it more or less troublesome. Certain types of particles are more problematic than other types, depending on the process. For example, copper diffuses through oxides and silicon. Copper is soluble in silicon at processing temperatures and diffuses throughout the bulk silicon very rapidly. On cooling, the copper precipitates as copper silicide (Cu.sub.3Si) on the surface of the wafer, damaging the wafer and thereby reducing the yield. Because of copper's high diffusivity, even particulate contamination on the backside of the wafer can damage the frontside of the wafer. Nickel, iron, and other metallic contaminants present similar problems, but to a lesser extent. [0006] Consequently, it is important to accurately detect particles in the manufacture of integrated devices. It is also important to determine the compositions of the particles. SUMMARY OF THE INVENTION [0007] Making a particle on a substrate larger would make it easier to detect, and would also permit counting particles with sizes below the detection limit of the detection device, thereby improving the sensitivity or resolution of the device. Detecting a greater percentage of the particles contaminating a substrate would improve yields. [0008] Furthermore, existing particle counting devices do not distinguish between types of particles. Distinguishing between types of particles is useful in both the front end of the line (FEOL) and the back end of the line (BEOL), as well as at intermediate points in the processing cycle. At the front end of the line, a specification for particles based on their compositions would improve yields. For example, silicon particles at a particular density and of a certain size on the backside of a wafer may have no effect on a certain process, while copper particles at the same density and size lead to low yields. At the back end of the line, identifying the compositions of one or more particulate contaminants after processing is useful in quality control, permitting monitoring, improving, or validating a process. [0009] An embodiment of the disclosed method provides a method for detecting a particle on a substrate, wherein the substrate is used in the fabrication of an integrated device. The method comprises at least the steps of (1) contacting the substrate with a monomer, wherein the particle catalyzes the polymerization of the monomer, and (2) detecting the particle using a particle counter. In another embodiment, the composition of a particle may be identified by determining the rate of the polymerization reaction. [0010] Another embodiment provides a method for detecting a particle on a substrate used in integrated device fabrication, the method comprising at least the steps of (1) obtaining a first particle detection on the substrate; (2) contacting the substrate with a first monomer, wherein the particle catalyzes the polymerization of the monomer; (3) obtaining a second particle detection on the substrate; and (4) comparing the results of the particle detection steps to identify the particle. This embodiment is used to identify a first type of particle, which catalyzes the polymerization of the first monomer. Another embodiment provides a method of also identifying a second type of particle by adding the steps of (5) contacting the substrate with a second monomer, the polymerization of which is catalyzed by a second type of particle; (6) obtaining a third particle detection on the substrate; and (7) comparing the results of the particle detection steps to identify a particle of a second type of particle. [0011] Preferably, the particle counter detects the number, sizes, and/or positions of particles on the substrate. Certain particle counters are capable of detecting particles on both sides of the substrate without unmounting the substrate. In a preferred embodiment, the particle counter detects particles optically, for example, using a laser scanner, or by detecting the absorbance, fluorescence, reflectance, refractive index, or polarization of a particle. [0012] In one embodiment, the method detects a metal particle, for example copper. Preferably, the substrate is silicon, more preferably, a single crystal silicon wafer. [0013] In certain embodiments, the monomer is polymerized by a plurality of particle types. In another embodiment, the substrate is contacted with a plurality of monomers, either simultaneously, sequentially, or in a combination thereof. [0014] In some embodiments, the monomer is in the vapor phase. Preferably, the monomer is an alkene, for example, styrene, methyl acrylate, ethyl acrylate, methyl methacrylate, or acrylonitrile. In another embodiment, the monomer is aniline or thiophene. [0015] One embodiment further comprises an initiator, for example, benzyl bromide. In another embodiment, the substrate is irradiated with electromagnetic radiation. BRIEF DESCRIPTION OF THE DRAWINGS [0016] FIG. 1 illustrates an embodiment of the disclosed method for detecting particles on a substrate. [0017] FIG. 2 illustrates another embodiment of the disclosed method for detecting particles on a substrate. [0018] FIG. 3A and FIG. 3B illustrate the output of a particle counter for a silicon wafer before and after exposure to a monomer according an embodiment of the disclosed method. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT [0019] As used herein, the term "type of particle" means a composition or material of which a particle is composed. For example, "copper" and "silicon" are types of particles. A single "type" may include more than one composition, for example, "metal" is a type of particle, as is "copper compounds." A particle with a composition of interest is also referred to herein as a "target." The term "lower alkyl" is used in its normal sense, as well as to mean alkyl groups having from 1 to about 6 carbon atoms, and may be straight-chained, branched, cyclic, or combinations thereof. The term "monomer" refers to a composition rather than a single molecule. Similarly, the term "monomers" refers to a plurality of monomer compositions rather than a plurality of monomer molecules. "Growth" of a particle refers to the formation of polymer on the surface of a particle, thereby increasing the size of the particle. Continue reading about Particle detection method... Full patent description for Particle detection method Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Particle detection method patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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